1. Field of the Invention
The present invention relates to a disk cartridge that rotatably houses therein a disk-shaped recording medium such as an optical disk or a magnetic disk, and in particular, to a disk cartridge of a type capable of sliding a shutter thereof in both rightward and leftward directions with respect to a neutral position in which the shutter closes a window for allowing a head to gain access therein and for allowing a drive shaft to be inserted therein.
2. Description of the Related Arts
Conventionally, in order to load an equipment or a device with a disk-shaped recording medium such as an optical disk or a magneto-optical disk, a disk cartridge that rotatably houses therein the disk-shaped recording medium has been employed. This disk cartridge is provided with a window for allowing a head to gain access therein and for allowing a drive shaft to be inserted therein, and this window is constructed to be opened and closed by a shutter that has a generally bracket-like shape in cross sectional and is slidably provided on the surface of the disk cartridge. When this disk cartridge is loaded into a disk drive unit, the window is opened by sliding the shutter of the disk cartridge by a shutter drive pin of the disk drive unit for the purpose of executing operations to read and write on the disk.
In a disk cartridge that houses therein a disk capable of being read and written on its both surfaces and that is able to be loaded into a disk drive unit with either one of the upper and lower surfaces being facing up, the shutter drive pin of the disk drive unit is driven in one direction and the shutter of the disk cartridge is made slidable in both the rightward and leftward directions relative to a neutral position in which the shutter closes the window for allowing a head to gain access therein and for allowing a drive shaft to be inserted therein, in order to prevent the shutter drive mechanism of the disk drive unit from being complicated.
As a shutter mechanism of this type, for example, there are disclosed:    (1) a mechanism that employs two torsion coil springs (Japanese Patent Publication No. HEI 5-6758), and    (2) a mechanism provided with a metallic guide shaft (Japanese Patent No. 2508449).Any of them has, however, such disadvantages as requiring a great number of components and as high cost. Particularly, in the mechanism (2), the slider and the shutter must be preliminarily connected to the guide shaft into a sub-assembly, and thereafter the sub-assembly must be connected to the cartridge casing. This causes a problem that the assembling work is difficult, and causes other problems.